The present invention disclosed herein relates to a film battery and more particularly, to a pouch-type flexible film battery and a method of manufacturing the same.
Recently, interests in flexible devices, such as a rollable display, e-paper, a flexible liquid crystal display (LCD), a flexible organic light-emitting display (OLED), and a wearable PC, has been rapidly increased. As a result, a power supply for the flexible devices has also been required to have flexible characteristics.
In consideration of operating environments, a flexible power supply has to be manufactured to have durability in addition to the flexible characteristics. For example, under a repeated bending motion, the flexible power supply has to be manufactured to satisfy that 1) cracks are not generated in respective components thereof, and 2) separation phenomena do not occur between the components thereof. In addition, in order to successfully introduce the flexible power supply in the market, reduction in the manufacturing cost of the flexible power supply is necessary. To reduce the manufacturing cost, it is favorable that the film battery is manufactured through a simple and continuous manufacturing process.
The flexible characteristics may be satisfied through manufacturing the components of the flexible power supply by using materials having ductile characteristics. However, it was difficult to simultaneously satisfy the durability and the flexible characteristics according to the technologies which have been suggested until now. For example, a polymer film having flexible characteristics (e.g., polyethylene terephthalate) was suggested as a packing material of the film battery. However, since most of the polymer films are not capable of completely blocking the penetration of moisture or gas as well as having insufficient corrosion resistance to strong acid or strong base, technical limitations such as the leakage or drying of an electrolyte may be generated.
Though some polymer films (e.g., polypropylene) have sufficiently large corrosion resistance to strong acid or strong base, these polymer films have other physical properties causing complexity in the manufacturing process of the film battery. For example, although screen printing is a method of forming a thin film that can reduce the manufacturing cost, formation of a layer directly on polypropylene is difficult through screen printing because polypropylene has low surface energy and hydrophobicity. In addition, according to the related art, contact property between electrodes and an electrolyte constituting the film battery deteriorated over prolonged operation. For example, separation between the electrodes and the electrolyte occurred or physical contact deteriorated.